OFFSET
1,1
COMMENTS
Since Q is odd, all prime divisors of 4+Q^2 are congruent to 1 modulo 4.
At least one prime divisor of 4+Q^2 is congruent to 2 modulo 3 and hence to 5 modulo 12.
The first two terms are the same as those of A057208.
LINKS
Tyler Busby, Table of n, a(n) for n = 1..15
EXAMPLE
a(3) = 17 is the smallest prime divisor congruent to 5 mod 12 of 4+Q^2 = 21029 = 17 * 1237, where Q = 5 * 29.
MATHEMATICA
a={5}; q=1;
For[n=2, n<=5, n++,
q=q*Last[a];
AppendTo[a, Min[Select[FactorInteger[q^2+4][[All, 1]], Mod[#, 12]==5 &]]];
];
a (* Robert Price, Jul 16 2015 *)
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Nick Hobson, Nov 18 2006
STATUS
approved